Which one of the following is NOT a correct expression for an ideal gas?

[$$\mathrm{C_p}=$$ Molar specific heat of a gas at constant pressure,

$$\mathrm{C_v}=$$ Molar specific heat of a gas at constant volume,

$$\mathrm{Y}=$$ Ratio of two specific heats of a gas,

$$\mathrm{R}=$$ Universal gas constant]

The molecular masses of helium and oxygen are 4 and 32 respectively. The ratio of r.m.s. speed of helium at 327$$^\circ$$ to r.m.s. speed of oxygen at 27$$^\circ$$ will be

Which one of the following p-V diagram is correct for an isochoric process:

Assume that for solar radiation, surface temperature of the sun is $$6000 \mathrm{~K}$$. If Wien's constant 'b' is $$2.897 \times 10^{-3} \mathrm{~mK}$$, the value of maximum wavelength will be